Multiple aperture memory core



1965 w. F. EIS EMAN ETAL 3,214,745

MULTIPLE APERTUHE MEMORY CORE Filed Aug. 23. 1962 2 Sheets-Sheet l PRIOR ART PRIOR ART G IGQM Fig.3. Fig.4.

WITNESSES w F INEYENTOR 1am IS n Q John C. Donoh MW ATTORN Y Oct. 26, 1965 w. F. EISEMAN ETAL 3,214,745 MULTIPLE APERTURE MEMORY CORE Filed Aug. 25, 1962 2 Sheets-Sheet 2 United States Patent Ofiice 3,214,745 l atented Oct. 26, 1965 3,214,745 MULTHLE APERTURE MEMORY CORE William F. Eiseman, West River, and John C. Donohue,

Hanover, Md., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvauia Filed Aug. 23, 1962, Ser. No. 219,036 4 Claims. (Cl. 340174) The present invention relates generally to memory cores and more particularly to multiple aperture memory cores of improved geometry.

Magnetic cores are provided with a number of apertures, both major and minor, to provide multiple flux paths for a closer degree of control over the information stored therein. Cores of conventional geometry make wiring difficult and place limitations on core spacing within a memory frame. When the windings such as sense, drive and inhibit are threaded straight through the major aperture of the core, usually at right angles to each other, each core must be orientated at an angle with such windings. As a result, the interrogate windings which must pass through the much smaller minor apertures are unable to be run straight through thus making the wiring much more difficult and placing limitations on core spacing within the memory frame.

The response to interrogation is always limited to the flux path of smallest cross-sectional area. Other crosssectional areas not of first order effect in determining core characteristics are then merely excess core material adding to the expense and volume of the memory frame.

In accordance with the present invention, slotted interrogate holes are provided as minor apertures providing for straight wiring runs in a memory frame thereby minimizing electrical shorts and broken wires and making assembly much easier. Excess material is removed from the conventional circular memory core by forming such core in a substantially elliptical geometry. Both the slotted minor aperture and the elliptical core geometry combine to provide a 40% increase in packaging density within a memory frame while at the same time incurring no penalty in easily assembling such frames.

Therefore, an object of the present invention is to provide a multiple aperture core of improved geometry.

Another object of the present invention is to provide a multiple aperture core having slotted minor apertures Another object of the present invention is to provide for straight through wiring runs.

a multiple aperture core shaped in such a manner as to insure that all the core material is utilized.

A further object of the present invention is to provide a memory core array 'having straight wiring runs and increased packaging density.

Further objects and advantages of the present invention will be readily apparent from the following detailed description taken in conjunction with the drawing in which:

FIGURE 1 is a representation of a typical geometrical configuration of a multiple aperture core of the prior art;

FIG. 2 is a schematic representation of a magnetic core array of the prior art;

FIG. 3 is a schematic representation of an illustrative embodiment of the present invention;

FIG. 4 is a schematic representation of another illustrative embodiment of the present invention; and

FIG. 5 is a fragmentary perspective view of a magnetic core array including a plurality of cores as shown in FIG. 3.

A conventional multi-aperture core 2, of the type used in non-destructive read-out memory systems, is shown in FIG. 1. It can be seen that the core outline and its major and minor apertures are all of circular configuration. This leads to two distinct disadvantages. In practical layouts of memory planes, the cores must be interconnected in both vertical and horizontal directions. From FIG. 2 it can then be seen that the cores 2 themselves are then most naturally located at 45 angles with respect to these axes. For example, each core 2 is disposed at 45 mechanical degrees with the drive winding 4 in a horizontal direction and the sense and inhibit windings 6 in the vertical direction.

From FIG. 2 it is evident that the drive windings 4 and the sense and inhibit windings 6, which pass through the large major aperture, can be run straight and are relatively easy to string during assembly. The interrogate windings 8 which must pass through the much smaller minor apertures however, cannot be run straight. This makes the wiring much more difficult and places a limitation on the core spacing, depending on tolerable wire bend and the ability to get the wire through the holes.

The second disadvantage of a core of conventional geometry is the wasted core material of little effect in determining the core characteristics but large in taking up valuable space within the memory frame. As mentioned previously, a first order factor in the electrical characteristics of a core is the cross-sectional area of the core. This area is figured at the least area point. The result is unnecessary core material requiring valuable space and resulting in an unnecessary increase in switching time due to the additional unused mass of the core.

FIG. 3 illustrates a core in accordance with the present invention but expanded on a scale approximately eight times its usual size for purposes of clarity. A core 12 is provided with a major aperture 14- and two minor apertures 16. Each minor aperture is of rectangular slot configuration with opposite ends on the major axis rounded to receive the interrogate windings. To provide for straight runs of the interrogate windings the major axis of such slots 16 is made substantially equal to the thickness of the core 12 plus the wire thickness to be inserted therethrough. The minor axis of the minor aperture or slots 16 is made substantially equal to the thickness of the wire. Both the major and minor axes of the minor apertures 16 may be varied slightly to provide for the usual clearance variances which may occur.

In practice, the geometry of the minor apertures 16 approximately doubles the minor hole peripheries and this increased ratio in respect to the circumference of the major aperture 14 tends to decrease readout. Experiment shows however, that the decreased ratiov is in the order of one-third. The result is a good trade for ease in wiring and greatly increased packaging density. It has been calculated that better than. 20% volume reduction is obtained in an assembled memory stack due to forming the minor apertures in a manner shown in FIG. 3.

Circular cores of the prior art generally have the smallest cross-sectional area located between a minor aperture 16 and the major aperture 14. Therefore, to eliminate excess core material not of a first order factor in the electrical characteristics of the core 12, the core, in accordance with the present invention, has been made of elliptic cylinder configuration. Core material offering a greater cross-sectional area to flux density has been eliminated from the conventional circular memory core. Core mateial has been removed at locations around the core away from the interrogate holes 16 so that the cross-sectional area extending between any aperture and the periphery of the core 12 is substantially equal to the limiting cross-sectional area between the major aperture 14 and the minor aperture 16. In this manner 20% greater packaging density is achieved.

FIG. 4 illustrates an alternate illustrative embodiment of the present invention which also eliminates ineffective core material but eliminates such material in-a more economical manner. Instead of fashioning the core in an elliptic cylinder configuration as shown in FIG. 3, arc segments located perpendicular to the major axes of the minor apertures 16 are removed from the conventional circular cores. The alternate embodiment of FIG. 4 also provides at least a 20% increase in packaging density.

FIG. illustrates a magnetic core array utilizing cores of geometric configuration shown in FIG. 3. Each bit of the magnetic core array is physically represented by a multiple aperture ferrite core in the frame 20. The frame is subdivided into two horizontal memory planes with the planes laying one above the other. Considering a particular memory plane, all the cores 22 are similarly oriented with respect to each other but are rotated at substantially 90 mechanical degrees to the cores 24 in an adjacent memory plane of the frame 20. It is to be noted that each core is also set at substantially mechanical degrees to the axes of the windings passing straight through the major aperture 25. The interrogate lines 26 pass, when utilizing a core of the present invention, straight through a word of the magnetic core array by extending through each bit of the word by means of one of the minor apertures 27 of all the cores in one word. The interrogate lines are then returned through another minor aperture 27 of each of the same cores to terminate at the same side of the frame 20 where they began.

Hence, it is readily apparent that the core geometry of the present invention allows straight through wiring of the interrogate windings in a magnetic core array thereby minimizing electrical shorts and broken wires while providing for an increase in package density. At the same time the elimination of unactive core material by providing a core configuration of substantially elliptic cylinder outline further increases packaging density.

While the present invention has been described with a particular degree of exactness for the purpose of illustration, it is to be understood that all equivalents, alterations and modifications within the spirit and scope of the present invention are herein meant to be included. For example, the windings or wires illustrated in FIG. 5 as extending through each core have been shown as contained in tubing for isolation purposes. It is to be understood that the term wire used herein is meant to include such tubing when used and the diameter of wire enclosed in the tubing is to include the diameter of such tubing when the length of the major and minor axes of minor apertures are to be determined. The use of such tubing is extraneous to the present invention but is fully described and claimed in our copending application, Serial 4 No. 199,097, filed May 31, 1962, and assigned to the same assignee.

We claim as our invention:

1. A magnetic core having a major aperture and at least one minor aperture; each said minor aperture having a major axis and a minor axis; said major axis being of a length substantially equal to the thickness of said core plus the thickness of the wire to be extended therethrough; said minor axis being of length substantially equal to the thickness of the wire to be extended therethrough.

2. A magnetic core having a major aperture and at least one minor aperture; each said minor aperture having a major axis and a minor axis; the major axis of each said minor aperture having a length substantially equal to the thickness of said core plus the thickness of the wire to be extended therethrough; the cross-sectional area between any aperture and the periphery of said core being substantially equal to the cross-sectional area between any two apertures.

3. In a magnetic core array; a plurality of magnetic cores each having a major aperture and at least one minor aperture; said cores arranged in word sequence; electrical lines extending through each said major aperture at mechanical degree angles to each other; other electrical lines extending through said minor apertures; each said minor aperture having a major axis substantially equal to the thickness of the core plus the thickness of said other electrical lines, whereby said other electrical lines are wired straight through a word.

4. A magnetic core having a major aperture and at least two minor apertures; each said minor aperture having a major axis and a minor axis; said major axes aligned in parallel relationship; said core having a circular configuration except for a removed segment perpendicular to the major axes of said minor apertures; the removed segments allowing the cross-sectional area of the remaining core between any aperture and the periphery of said core to substantially equal the smallest cross-sectional area between a minor aperture and a major aperture within said core.

References Cited by the Examiner UNITED STATES PATENTS 2,802,953 8/57 Arsenault et al 340-174 2,990,521 6/61 Shigeru Tominaga 340174 3,099,821 7/63 Post 340174 3,102,328 9/63 Schultz et al. 340-l74 3,146,393 8/64 Gibbon 340174 OTHER REFERENCES Publication 1, The Transfiuxor, by Rajchman and Lo, Proceedings of the IRE, March 1956, pages 321 to 332.

IRVING L. SRAGOW, Primary Examiner. 

2. A MAGNETIC CORE HAVING A MAJOR APERTURE AND AT LEAST ONE MINOR APERTURE; EACH SAID MINOR APERTURE HAVING A MAJOR AXIS AND A MINOR AXIS; THE MAJOR AXIS OF EACH SAID MINOR APERTURE HAVING A LENGTH SUBSTANTIALLY EQUAL TO THE THICKNESS OF SAID CORE PLUS THE THICKNESS OF THE WIRE TO BE EXTENDED THERETHROUGH; THE CROSS-SECTIONAL AREA BETWEEN ANY APERTURE AND THE PERIPHERY OF SAID CORE BEING SUBSTANTIALLY EQUAL TO THE CROSS-SECTIONAL AREA BETWEEN ANY TWO APERTURES. 